Electrode and contact element



' not become brittle,

Patented July 1, 1930 AMBROSE J. HANDELL, 0] WESTII'IELD, NEW JERSEYELECTRODE AND CONTACT ELEMENT Io Drawing. Application filed May 19,

This invention relates to electrode and contact elements which aresubject to electrlc arcs, such as the contact elements of timing devicesand circuit makin and breaking devices and the electrodes 0 spark plugs.

Heretofore the most satisfactory materials obtainable for themanufacture of such elements were platinum and alloys of platinum withother metals of the platinum grou The extremely high cost and scarcityof suc metals render their use prohibitive on any large scale. Among thebase metals, tungsten is fairl satisfactory for contact points but isaltogether unsatisfactory for spark plug electrodes because it oxidizesvery rapidly at even moderately high temperatures and is also quiteexpensive in the ductile condition. The spark plug electrodes have beenheretofore commonly manufactured from pure nickel, various alloys ofnickel and manganese, and Monel, which is an alloy of mckel, copper,manganese and iron. These materials have been fairly satisfactoryheretofore but with the developement of the modern high speed internalcombustion motor, the service conditions have become more and moresevere, so that the necessity of a bet ter electrode material has beenimperative.

Among the qualities, which are desirable in an alloy for such elements,the following may be mentioned 1. Ability to withstand the cutting andabrading action of an electric spark or high voltage are, while themetal is at a high temperature.

2. Resistance to oxidation at high temperatures, and to corrosion byproducts of combustion.

3. Ability to withstand deterioration by changes in internal structureunder the conditions of service, so that the electrode does but remainstough and ductile.

4. High thermal conductivity and high or fairly high electricalconductivity.

5. Small tendency to absorb carbon under the service conditions orability to remain strong and tough whether or not carbon is absorbed.

6. Sufficient strength, toughness, mallea- 1925. Serial No. 81,458.

bilit and ductility to allow working into the nished form by ordinarymethods, and hardness not too great to allow easy machining of thefinished material.

I have discovered that by the addition of suitable proportions ofsilicon or silicon and certain other elements to nickel, an element maybe produced which exhibits far greater durability in such service thanany other base metal alloy previously known.

Increased ability to withstand the cutting and abrading action of thespark is con ferred upon nickel by additions which increase the hardnessand strength at hi h temperatures, and the resistance to oxidation. Notall additions which produce this effect are suitable, however, becausemany of them have a bad effect upon the other properties, such asthermal and electrical conductivity, ductility, etc. Even smalladditions of silicon have a powerful hardening effect, and greatlypromote the resistance to oxidation, and these effects are retained athigh temperatures.

Additions of chromium and tungsten will harden nickel, but in order toproduce the effeet of a given addition of silicon, so much more chromiumor tungsten must be added that the thermal conductivity of the resultantalloy is lowered very much more, and the electrical resistance is verymuch increased. This effect is so pronounced that the usefulness of thealloys is practically destroyed.

Alumium has a similar eflect in hardening nickel and promotingresistance to oxidation, but the accompanying bad efiects are not sopronounced as for chromium or tungsten. The hardening effect ofzirconium is great, but the resistance to oxidation obtained by additionof zirconium is not so high, and the high cost of zirconium is a greatdisadvantage. The same remarks apply to titanium and vanadium.Therefore, while small amounts of any or all of these metals may be 7added, to the alloy, amounts to be added must 95 not be excessive, andthey will not serve to replace all of the silicon. If sufficient siliconis present, none of these metals need be added.

Addition to nickel of suflicient silicon, or of 100 silicon plus theother metals mentioned, to produce the required resistance to cuttingand abrasion, to oxidation, and to deterioration of structure at hi htemperatures will lower the ductility ant? toughness considerably, ascompared to pure nickel. These latter ualities can be greatly improvedby the furt er addition to the alloy of a suitable proportion ofmanganese, without harm to the previously mentioned qualities, and thiseffect of the manganese is so valuable that while manganese is not anabsolutely essential constituent, the alloys containing a certain amountof man anese are decidedly preferable to those wh ch contain nomanganese, or only trifling amounts. Too much manganese should not beadded. as it will cause a lowering of the thermal conductivity, andthereby automatically raise the operating temperature of the electrodeswhen in service, which will of course mean increased severity of theworking conditions and conse uently a shorter life.

etals such as copper and iron should not be present it they can beavoided. These metals are of little or no value in promoting thedesirable qualities, and they will reduce the thermal conductivitymarkedl if more than trifling amounts are present. 11 also has the badeffect in these alloys of reducing the resistance to oxidation, and whenmuch is present, of causing brittleness, nullifying the beneficialefiect of the manganese addition.

The percenta es of the various constituents of the alloy w ich have beenfound b experiment to be preferable and desirab e are the followingSilicon should be present in amounts pref erably not to exceedapproximately 6 to 7%. Above these percentages the alloy becomes so hardas to be practically unworkable by ordinary methods, which of coursedestroys its usefulness for this purpose, although m castings, muchlarger amounts might be used. The referable addition is from 3 to 5% inwhich range the alloy is strong, quite tou h and ductile, and exhibitsall the good ua ities previously enumerated. Addition 0 silicon inamounts less than three per cent is of very marked benefit, but with thesmaller additions the benefit to be obtained is of course also less.

Manganese should preferably be present in amounts of approximately 2%,and not great- 1y to exceed approximately 5%. The beneficial effect onthe toughness and ductilit of an addition of manganese is very marked,but if more than about 5% is present the thermal conductivity is loweredconsiderably, without compensating increase of toughness and ductility.If less than about of 1% or so is present, the effect is small. whilewith additions of about 2%, the beneficial effects are very pronounced,without any marked decrease in thermal or electrical conductivity,

as compared with alloys containing little or no manganese.

Any or all of the elements, aluminum, chromium, tungsten, zirconium,titanium, and vanadium may be used to replace a portion of the silicon,but they should not be used to re lace all or a major portion of thesilicon. eir combined total should not exceed the total of the siliconresent, and the total of these elements lust e silicon should not muchexceed the mentioned as the practical limit for silicon, for althoughtheir efiects on the ductility are less, their efiects on the thermalconductivity and electrical resistance are greater.

Iron is of no benefit to the alloy, and should be kept as low aspossible, because of its bad effects on the resistance to. oxidation,the toughness and the thermal and electrical conductivities. It shouldpreferably be present only in such amounts as are unavoidable whenworking with commercial materials.

The bad effects of copper are much less pronounced, but as cop r is ofno benefit, it also should be kept as ow as possible.

Elements such as sul hur, carbon, phosphorus, etc., should be ept as lowas possible, because of their bad effects on the mechanical roperties.

The ba ance of the alloy should be nickel. I am aware that cobalt may besubstituted for nickel, in this alloy, but the high price of cobalt, ascompared with that of nickel makes it, at the present time, anundesirable substitute for nickel, and it ofiers no compensatingadvantage over nickel. When mckel is used the amount of cobalt presentshould be small, and when cobalt is used the amount of nickel presentshould be small, for when large amounts of these elements are presentsimultaneously, the thermal and electrical conductivities of theresultant alloy are considerably lowered, which is an undesirableefiect.

Commerical nickel frequently contains a small amount of silicon, usuallyless than of 1 rcent, and it is necessa tiona silicon to the commercianickel so that the silicon content will be at least of 1 percent ormore.

It will be understood that by the term nickel, I intend cobalt to beconsidered as an equivalent substitute and that the electrode andcontact elements are formed of an allo of nickel with an added quantityof si icon and referably also man anese with optionally t e addition ofsmal quantities of other substances, all as specified in the ap ndedclaims.

t will be obvious that the specific instances, which have been givenherein, are intended solely for the purpose of explaining the-nature ofthe invention, and that, therefore, various changes in the details andproto add addi- III portions may be made b those skilled in the artwithin the princip e and scope of the invention, as expressed in theappended claims.

I claim 1. Electrode and contact elements subject to electric arcs, suchas for timing devices, spark plugs, and circuit making and breakingdevices, said elements bein formed of an alloy comprising a base ofnickel with an added quantity of substances selected from the groupconsisting of silicon, alumium, chromium, tungsten, zirconium, titanium,manganese, and vanadium, the substances added from said group includingat least silicon, and constituting between 1 and 5% of the alloy.

2. Electrode and contact elements subject to electric arcs, such as fortiming devices, spark plugs, and circuit making and breaking devices,said elements being formed of an alloy comprising a base of nickel withan added quantity of substances selected from the group consisting ofsilicon, aluminum, chromium, tungsten, zirconium, titanium, manganese,and vanadium, the substances added from said group includin at leastsilicon, the silicon constituting atdeast 40% of the added substances.

3. Electrode and contact elements subject to electric arcs, such as fortiming devices, spark plugs, and circuit making and breaking devices,said elements being formed of an alloy comprising a base of nickel withan added quantity of substances selected from the group consisting ofsilicon, aluminum, chromium, tungsten, zirconium, titanium, ma anese,and vanadium, the substances added rom said group including at leastsilicon, and constitutlng less than 10% of the alloy.

4. Electrode and contact elements subject to electric arcs, such as fortiming devices, spark plugs, and circuit making and breaking devices,said elements being formed of an alloy comprising a base selected fromthe group comprising nickel and cobalt with an added quantity of siliconin an amount between 2 to 5%.

5. Electrode and contact elements subject to electric arcs, such as fortiming devices, spark plugs, and circuit making and breaking devices,said elements being formed of an alloy comprising a base selected fromthe group comprising nickel and cobalt with an added quantity of siliconand manganese, the silicon addition varying between of 1% and 10%, andthe manganese varying between nothing and 5%.

6. Electrode and contact elements subject to electric arcs, such as fortiming devices, spark plugs, and circuit making and breaking devices,said elements being formed of an alloy comprising a base selected fromthe group comprising nickel and cobalt with an AMBROSE J. MANDELL.

